---
title: "Merge customers · Customers · COUNT Partner API"
description: "Folds one or more duplicate customers into a target customer. POST /partners/customers/merge"
canonical: "https://developers.getcount.com/reference/customers/merge-customers"
source: "https://developers.getcount.com/reference/customers/merge-customers"
---
[Customers](https://developers.getcount.com/reference/customers) / Merge customers

# Merge customers

POST `/partners/customers/merge`

Folds one or more duplicate customers into a target customer.

Repoints every record on the source customers — invoices, transactions, projects, documents, contacts, addresses, notes and more — at the target, then soft-deletes the sources. This runs in a single transaction and cannot be reversed through the API. Call Preview a customer merge first.

HMAC signature + Bearer access token

[Try this request](https://developers.getcount.com/tools/try-it?method=POST&path=%2Fpartners%2Fcustomers%2Fmerge&body=%7B%0A++%22targetCustomerUuid%22%3A+%22dfa3219e-6af8-4c53-997a-037534f63a35%22%2C%0A++%22sourceCustomerUuids%22%3A+%5B%0A++++%227c8d9e0f-1a2b-4c3d-8e4f-5a6b7c8d9e0f%22%0A++%5D%0A%7D)

[Invoices API](https://developers.getcount.com/reference/invoices) [Projects API](https://developers.getcount.com/reference/projects) [Recurring Invoice Templates API](https://developers.getcount.com/reference/recurring-invoice-templates)

#### Request body

`targetCustomerUuid` uuid required

The customer that survives the merge and receives every reference.

`sourceCustomerUuids` array required

Customers to fold into the target and soft-delete. Non-empty, capped at 100 per request. The target UUID is ignored if it also appears here, and duplicates are collapsed.

#### Responses

`200` Merge committed. The merged customer is returned at the top level, not under `data`.

`400` targetCustomerUuid missing, sourceCustomerUuids empty or over 100 entries, no distinct source left after the target is excluded, or a source is a firm-managed customer.

`404` The target or one of the source customers was not found in this workspace.

`401` Missing or invalid HMAC signature, expired timestamp, or invalid Bearer token. [Troubleshoot](https://developers.getcount.com/getting-started/errors#error-401)

`403` The credential does not have access to this workspace or resource. [Troubleshoot](https://developers.getcount.com/getting-started/errors#error-403)

`429` Rate limit exceeded (100 requests per minute per clientId). Retry after the Retry-After header. [Troubleshoot](https://developers.getcount.com/getting-started/errors#error-429)

[Previous POST Preview a customer merge](https://developers.getcount.com/reference/customers/preview-merge-customers)

POST `https://api.getcount.com/partners/customers/merge`

Request

```javascript
import crypto from 'node:crypto';

const BASE_URL = 'https://api.getcount.com';
const CLIENT_ID = process.env.COUNT_CLIENT_ID;
const CLIENT_SECRET = process.env.COUNT_CLIENT_SECRET;
const ACCESS_TOKEN = process.env.COUNT_ACCESS_TOKEN;

const method = 'POST';
const signingPath = '/customers/merge';
const timestamp = Math.floor(Date.now() / 1000).toString();
const body = {
  "targetCustomerUuid": "dfa3219e-6af8-4c53-997a-037534f63a35",
  "sourceCustomerUuids": [
    "7c8d9e0f-1a2b-4c3d-8e4f-5a6b7c8d9e0f"
  ]
};
const bodyString = JSON.stringify(body);

const bodyHash = crypto.createHash('sha256').update(bodyString).digest('hex');
const baseString = `${method}:${signingPath}:${timestamp}:${bodyHash}`;
const signature = crypto.createHmac('sha256', CLIENT_SECRET).update(baseString).digest('hex');

const response = await fetch(`${BASE_URL}/partners/customers/merge`, {
  method,
  headers: {
    'x-client-id': CLIENT_ID,
    'x-timestamp': timestamp,
    'x-signature': signature,
    'Content-Type': 'application/json',
    Authorization: `Bearer ${ACCESS_TOKEN}`,
  },
  body: bodyString,
});

console.log(await response.json());
```

Response · 200

```json
{
  "message": "Successfully merged 1 customer(s) into Acme Corporation",
  "customer": {
    "id": "dfa3219e-6af8-4c53-997a-037534f63a35",
    "customer": "Acme Corporation",
    "email": "contact@acme.com",
    "mainPhone": "+1234567890",
    "website": "https://acme.com",
    "status": "active",
    "notes": "Preferred customer. Net-30 terms.",
    "paymentTerm": "net30",
    "taxNumber": null,
    "taxAutoCalculate": false,
    "taxExcluded": false,
    "contactName": "John Doe",
    "billingAddress": {
      "id": "0b2c1f5e-7a9d-4f2b-9c1e-2a4b6d8e0f12",
      "street": "123 Main St",
      "city": "San Francisco",
      "state": "CA",
      "zipCode": "94102",
      "country": "USA"
    },
    "shippingAddress": null,
    "contacts": [
      {
        "id": "a5da3577-bf85-4e3a-aa73-df85ca69bc67",
        "firstName": "John",
        "lastName": "Doe",
        "email": "john@acme.com",
        "phone": "+1234567890",
        "isPrimary": true
      }
    ],
    "taxes": [],
    "salesRep": null,
    "createdAt": "2026-01-15T10:30:00.000Z",
    "updatedAt": "2026-01-28T14:22:30.000Z"
  },
  "mergedCount": 1
}
```